Along with the recent popularization of data communication networks, a so-called home network, in which home appliances, computers, and other peripheral devices are connected to a network so that the respective devices can communicate with each other at home, has been becoming widespread. The home network provides a user with convenience and comfort, e.g., communication between devices connected to the network allows share of data processing functions of the respective devices and transmission/reception of content between the devices. The home network is expected to become more and more widespread in the future.
UPnP has been known as a protocol suitable for a configuration of such a home network. UPnP is capable of easily establishing a network without any complicated operation and enables a device connected to the network to receive services provided by respective connected devices without any difficult operation or setting. Also, UPnP has advantages of not depending on an OS (Operating System) on a device and of allowing easy addition of a device.
In UPnP, definition files compatible with XML (eXtensible Markup Language) are exchanged between connected devices, and mutual recognition is performed between the devices. An outline of processes of UPnP is as follows.
(1) Addressing process of obtaining an own device ID, such as an IP address
(2) Discovery process of searching for respective devices on a network, receiving responses from the respective devices, and obtaining information included in the responses, such as the type and function of the devices
(3) Service requesting process of requesting services to the respective devices on the basis of the information obtained in the discovery process
Execution of the above-described process procedure enables provision and receipt of services applying the devices connected to the network. A device newly connected to the network obtains a device ID through the above-described addressing process and obtains information about the other devices connected to the network through the discovery process, thereby being capable of requesting a service to another device on the basis of the obtained information.
For example, a server that stores various pieces of audio and image content and that performs a service of providing a client with the content in response to a request from the client has the CDS (Content Directory Service) as a function of executing a content managing process.
The CDS (Content Directory Service) manages content stored in storage means of the server, e.g., storage means such as a hard disc or a DVD, by using a content managing directory having a hierarchical structure. The CDS (Content Directory Service) holds a content list having a branched-tree hierarchical structure based on unique classification applying metadata corresponding to content, such as a genre and an artist, and executes content management based on the content list.
When content such as audio data or image data managed by the server is to be reproduced in a client, the client transmits a request for obtaining content information to the server. The server presents the content list managed in the CDS to the client, and the client selects desired content from the content list and executes a request for obtaining the content to the server. With this process, the client can obtain the specific content from the server and reproduce it. Incidentally, a configuration of such a process of storing and reproducing content is described in Patent Document 1, for example.
On the other hand, the client can provide the server with content held in a storage unit of the client and set the content as CDS (Content Directory Service)-managed content in the server. This process enables other clients connected to the network to obtain, reproduce, and use the newly stored content. Specifically, for example, the following processes are possible: a process of outputting audio and image content individually obtained by the client via the network to the server and setting the content as server-managed content; and a process of setting image data captured by a digital camera as server-managed content when the client is a digital camera.
However, the server executes content management based on the content list in the CDS, and the client specifies a content storage site in the server on the content list presented by the CDS. Therefore, even when the server holds various storage means such as a hard disc and a DVD, for example, the client cannot request storage of content with specified storage means to the server.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-348455